Refactor event handler syntax for radio buttons

Author: gammasoft71

examples/xtd.forms.examples/events/enable_changed_event/src/enable_changed_event.cpp

@@ -8,25 +8,25 @@ namespace enable_changed_event_example {
       radio_button1.name("radio_button1");
       radio_button1.size({100, 17});
       radio_button1.text("button1");
-      radio_button1.enabled_changed += event_handler(*this, &form1::radio_button1_enabled_changed);
+      radio_button1.enabled_changed += event_handler {self_, &form1::radio_button1_enabled_changed};
 
       radio_button2.location({0, 39});
       radio_button2.name("radio_button2");
       radio_button2.size({150, 17});
       radio_button2.text("Disable button1");
-      radio_button2.checked_changed += event_handler(*this, &form1::radio_button2_checked_changed);
+      radio_button2.checked_changed += event_handler {self_, &form1::radio_button2_checked_changed};
 
       client_size({292, 273});
       controls().add_range({radio_button1, radio_button2});
       name("Form1");
     }
 
   private:
-    void radio_button1_enabled_changed(object& sender, const event_args& e) {
+    auto radio_button1_enabled_changed(object& sender, const event_args& e) -> void {
       message_box::show("This button has been disabled.");
     }
 
-    void radio_button2_checked_changed(object& sender, const event_args& e) {
+    auto radio_button2_checked_changed(object& sender, const event_args& e) -> void {
       radio_button1.enabled(false);
     }